This application claims the benefit of International Application PCT/JP00/05919 filed Aug. 31, 2000 and which published in the Japanese language with an English abstract only as WO 01/16198 on Aug. 3, 2001.
The present invention relates to a star block copolymer with an arm moiety having an alkenylphenol homopolymer or copolymer as polymer chains and a process for producing the same. The star block copolymer of the present invention is a compound anticipated to be utilized as a resist material for excimer lasers and electron beams.
Alkenylphenol homopolymers and copolymers of which poly-p-hydroxystyrene is a representative are useful as resist materials for excimer lasers of chemical amplification. Among them, resists using a poly-(p-hydroxystyrene) or (p-hydroxystyrene/styrene) copolymer are known as resists capable of imaging with high resolution.
In regards to star block copolymers, for example, in Japanese Unexamined Patent Publication No. 222114 of 1993, a star polymer has been described in which a block copolymer molecule is produced by anionic polymerization of isoprene and styrene, coupled with a polyalkenyl coupling agent at 2.5 moles or more per 1 mole of the block copolymer molecule, and further 95% or more of isoprene units (olefin unsaturated) and less than 15% of styrene units (aromatic unsaturated) are selectively hydrogenated.
Japanese Unexamined Patent Publication No. 220203 of 1994 has described a modified block copolymer comprising a core crosslinking with a polyfunctional coupling agent, and comprising at least one type of polymer block induced from unsaturated carboxylate ester of alkyl, and at least one type of polymer block induced from conjugated diene and/or at least one type of a polymer block induced from monovinyl aromatic compound.
Japanese Unexamined Patent Publication No. 256436 of 1994 has described a polymer comprising at least three first arms with peak molecular weight of from 10,000 to 200,000 comprising hydrogenated polymerization conjugated diene; at least three second arms with peak molecular weight of from 500 to 10,000 comprising polymerized methacrylate and/or an amido or imide derivative thereof; and a central core connecting the first arms and second arms in a star configuration and comprising polymerized bis unsaturated monomer.
Japanese Unexamined Patent Publication No. 97413 of 1995 has described a star block polymer having the general formula: 
wherein C is a block of crosslinked bis unsaturated monomer; each A is independently a block of anionic polymerization monomer; M is a block of polymerization methacrylic acid alkyl polymerized through ethylene unsaturation of methacrylic acid moiety; r is 0 or 1; and s and t are an average of 2 or more but sxe2x89xa6t wherein the molecular weight of from 20,000 to 2,000,000 and A is styrene or isoprene.
Japanese Unexamined Patent Publication No. 48987 of 1996 has described a star polymer having the structure represented by (EPxe2x80x2-S-EPxe2x80x3) n-X wherein EPxe2x80x2 is a first hydrogenated block of polyisoprene (Ixe2x80x2) with the number average molecular weight (Mn) before hydrogenation of from 10,000 to 100,000, S is polystyrene block with the average molecular weight (Mn) of from 6,000 to 50,000, EPxe2x80x3 is a second hydrogenated block of polyisoprene (Ixe2x80x3) with the number average molecular weight (Mn) before hydrogenation of from 2,500 to 50,000, a molecular ratio of Ixe2x80x2/Ixe2x80x3 is at least 1.4, X is a core consisting of a polyalkenyl coupling agent, and n is an average arm number per star molecule formed by reacting the polyalkenyl coupling agent at 2 moles or more for one mole of (EPxe2x80x2-S-EPxe2x80x3), wherein the star polymer consists of an intramolecular bound polystyrene block and hydrogenated polyisoprene block and is useful as an improver of the viscosity index (VI).
Japanese Unexamined Patent Publication No. 81514 of 1996 has described a polyfunctional initiator of anionic polymerization, which is soluble in non-polar solvents, not containing (or substantially not containing) any residual double bond and represented by the general formula, (PA)aNr.xe2x88x92nLi+ wherein PA represents a polymer block generated from at least one type of monomer A selected from vinyl aromatic monomers and diene monomers; a represents a number of arms of PA block, from 3 to 30, especially from 3 to 15; N represents a crosslinked core not containing or substantially not containing any residual double bond and has the formula, (PMc) (RLi) p wherein Mc is a monomer containing at least two polymerized double bonds per molecule; PMc is a crosslinked core of at least one type of polymerization monomer Mc containing from 3 to 30% residual double bonds for initial double bonds derived from monomer Mc; R is an alkyl group and the like having straight or branched chains; and p is a number of residual double bonds in PMc neutralized with RLi; n is a number of anion sites present in the crosslinked PMc core and equal to a+p (or p) (p has the above meanings, and a is a number of anion sites present in the crosslinked core before addition of RLi.)
Japanese Patent Publication No. 504865 of 1996 has described a star block copolymer comprising (a) at least three arms from at least one anion polymerized monomer selected from the group consisting of monovinyl aromatic hydrocarbon, conjugated diene and the mixtures thereof, (b) at least three arms comprising polydimethyl siloxane and (c) a core comprising a polyalkenyl aromatic coupling agent (the above (a) and (b) radiate out from this core).
Published Japanese Translation of PCT International Publication for Patent Applications No. 505179 of 1996 has described a block copolymer of the general formula (A-B)n(B) mX wherein A is a block of polystyrene having peak molecular weight of less than 15,000, B is a polymer block of hydrogenated conjugated diene having peak molecular weight ranging from 15,000 to 50,000, X is a block of divinylbenzene, and n and m are integers of 0 or more wherein a sum of n and m is at least 10.
Published Japanese Translation of PCT International Publication for Patent Applications No. 510236 of 1997 has described a star copolymer containing (a) four molecules or more of polyfunctional binders forming a core selected from the group consisting of divinyl aromatic compound, trivinyl aromatic compound, diepoxide, diketone, and aldehyde; and (b) three or more of cation polymer branches bound to said core wherein said polymer branch is selected from the group consisting of a homopolymer, copolymer and block copolymer having at least one polyolefin segment and at least one polyaryl segment, and a graft copolymer.
Polymers with higher molecular weights have been conventionally known to be more preferable as base polymers for positive resist materials in terms of resolution, heat resistance and the like. However, when a molecular structure of a base polymer is accompanied with high molecular weight as a conventional linear structure, it has been problematic in that resist viscosity is increased resulting in difficulty of spin coating though resist application on substrates is usually performed by spin coating.
Among the star block copolymers described above, those having a hydroxystyrene skeleton at an arm moiety have not been known.
The subject of the present invention is to provide a novel star block copolymer which can be made to have a high molecular weight as a solution and has a lower viscosity than solutions of linear polymers having the same molecular weight as the copolymer and which is expected to be used as a resist material; and a process for producing the copolymer.
As results of an intensive study to achieve said subject, the present inventors have found that the star block copolymer with a narrow molecular weight range having alkenylphenol skeletons of which structure is controlled is obtained by homopolymerizing by living anionic polymerization an alkenylphenol compound in which the hydroxyl group of the phenol moiety has been protected by protective groups or copolymerizing the alkenylphenol compound with a vinylaromatic compound, subsequently copolymerizing the resultant polymer using a polyvinyl compound to obtain a star block copolymer, and eliminating phenol hydroxyl protective groups with an acid reagent, and then completing the present invention based on these findings.
That is, the present invention relates to the star block copolymer described in any of the following (1) through (19):
(1) the star block copolymer characterized by having an arm moiety comprising a central core and a polymer chain radiated out from the central core, wherein the arm moiety (A) comprises the polymer chain (A1) having a repeated unit represented by the general formula (I): 
wherein R1 represents a hydrogen atom or a methyl group; R2 represents a hydrogen atom or a C1-C6 alkyl group; and p represents 1 or 2 wherein R2 may be identical or different when p is 2;
(2) the star block copolymer according to (1) characterized in that the polymer chain (A1) is a copolymer having repeated units represented by the general formula (I) and (II): 
wherein R3 represents a hydrogen atom or a methyl group; R4 represents a hydrogen atom or a C1-C6 alkyl group; R5 represents an acidolytic/leaving group; q represents 1 or 2 wherein R4 may be identical or different when q is 2;
(3) the star block copolymer according to (1) characterized in that the polymer chain (A1) is a copolymer having repeated units represented by the general formula (I) and (III): 
wherein R6 represents a hydrogen atom, a methyl group, or an aryl group which may have substituents; R7 represents a hydrogen atom or a C1-C6 alkyl group; r represents 1 or 2 wherein R7 may be identical or different when r is 2;
(4) the star block copolymer according to (1) through (3) characterized in that the polymer chain (A1) have repeated units represented in the general formula (I), (II) and (III) wherein R3, R4, R5, and q are the same as mentioned above;
(5) the star block copolymer according to any of (1) through (4) characterized in that the arm moiety (A) has the polymer chain (A1) and a polymer chain (A2) having a repeated unit (A21) represented by the general formula (IV): 
wherein R8 represents a hydrogen atom or a methyl group; R9 represents a hydrogen atom, a C1-C12 alkyl group, a hydrocarbon group having C3 or more alicyclic skeletons which may have substituents, an alkyl group having hydrocarbon groups having the alicyclic skeletons, or a heterocyclic group;
(6) the star block copolymer according to (5) characterized in that the polymer chain (A2) has the repeated unit (A21) represented by the general formula (IV) and a repeated unit (A22) represented by the general formula (V): 
wherein R10 represents a hydrogen atom, a methyl group, or an aryl group which may have substituents; R11 represents a hydrogen atom, a C1-C6 alkyl group, OR12 group wherein R12 represents a hydrogen atom, a C1-C6 alkyl group, or acidolytic/leaving group; t represents an integer of 0 or any of 1 through 3 wherein R11 may be identical or different when t is 2 or more.
(7) the star block copolymer according to (6) characterized in that the polymer chain (A2) is a block copolymerized by (A22) through (A21) sequentially from the central core;
(8) the star block copolymer according to any of (1) through (7) characterized in that the number average molecular weight of the polymer chains composing the arm moiety is in the range of from 1,000 to 100,000 and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of from 1.00 to 1.50;
(9) the star block copolymer according to any of (1) through (8) characterized in that the central core is the core crosslinked with a polyfunctional coupling agent;
(10) the star block copolymer according to (9) characterized in that the polyfunctional coupling agent is the compound having at least two polymerization double bonds per molecule;
(11) the star block copolymer according to (9) or (10) characterized in that the polyfunctional coupling agent is the compound represented by the general formula (VI): 
wherein R13 represents a hydrogen atom or a methyl group; Y represents an oxygen atom, a sulfur atom, R16R17N wherein R16 and R17 each independently represent hydrogen atoms, C1-C6 alkyl groups or alkoxycarbonyl groups, a methylene group which may have substituents, a phenylene group which may have substituents, C(R18R19)O, C(R18R19)S, C(R18R19)N(R20), OC(R18R19), SC(R18R19), N(R20)C(R18R19) (wherein R18, R19 and R20 represent C1-C6 alkyl groups, or phenyl groups which may have substituents), OCO, or CO2CH2; w represents an integer of 0 or 1 to 2 wherein Y may be identical or different when w is 2; and u represents 2 or 3 wherein Y, R13 and w may be identical or different;
(12) the star block copolymer according to any of (1) through (11) characterized in that the number average molecular weight is from 3,000 to 300,000;
(13) the star block copolymer according to any of (1) through (12) characterized in that the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of from 1.00 to 1.50; and
(14) the process for producing the star block copolymer according to any of (1) through (13) characterized in that by an anionic polymerization method using an anionic polymerization initiator as a polymerization initiator, the compound represented by the general formula (VII): 
wherein R3, R4, R5 and q are the same as mentioned above, is homopolymerized or copolymerized with the compound capable of copolymerizing the compound represented by the general formula (VII), subsequently the polyfunctional coupling agent (C) is copolymerized and the protective groups of phenol hydroxyl groups are eliminated;
(15) the process for producing the star block copolymer according to any of (1) through (13) characterized in that by an anionic polymerization method using an anionic polymerization initiator as a polymerization initiator, the compound represented by the general formula (VII) wherein R3, R4, R5 and q are the same as mentioned above, is homopolymerized or copolymerized with the compound capable of copolymerizing the compound represented by the general formula (VII), subsequently copolymerized with the polyfunctional coupling agent (C), further copolymerized with the compound capable of anion polymerizing, and then the protective groups of phenol hydroxyl groups are eliminated;
(16) the process producing the star block copolymer according to (14) or (15) characterized in that a molar ratio [(C)/(D)] of the polyfunctional coupling agent (C) to an active end of the polymer chain homopolymerizing the compound represented by the general formula (VII) or an active end (D) of the polymer chain copolymerizing the compound capable of copolymerizing with the compound represented by the general formula (VII) by the anionic polymerization method using the anionic polymerization initiator as the polymerization initiator, is from 1.0 to 10;
(17) the process for producing the star block copolymer according to any of (14) through (16) characterized in that the polyfunctional coupling agent is a compound represented by the general formula (VI): 
wherein Y, R12, R13, w and u are the same as mentioned above;
(18) the process for producing the star block copolymer according to any of (14) through (17) characterized in that the compound capable of copolymerizing with the compound represented by the general formula (VII) is a compound represented by the general formula (IX): 
wherein R6, R7, and r are the same as mentioned above; and
(19) the process for producing the star block copolymer according to any of (15) through (17) characterized in that the compound capable of anion polymerizing is a compound represented by the general formula (IX): 
wherein R8 and R9 are the same as mentioned above.
The star block copolymer of the present invention is not limited so long as the polymer chain comprises the polymer chain (A1) having the repeated unit represented by the general formula (I) in the arm moiety (A) in the star block copolymer having an arm moiety comprising a central core and a polymer chain radiated out from the central core, wherein in the repeated unit represented by the general formula (I), R1 represents a hydrogen atom or a methyl group; R2 represents a hydrogen atom or C1 through C6 alkyl group wherein, specifically, methyl group, ethyl, isopropyl and t-butyl groups can be exemplified; p represents 1 or 2 wherein R2 may be identical or different when p is 2 wherein substituted sites of R2 and the hydroxyl group (OH-group) are not especially limited but the hydroxyl group is preferably substituted at the para- or meta- position of an alkenyl group.
The above polymer (A1) chain is preferably copolymer having the repeated unit represented by the general formula (I) and the repeated unit represented by the general formula (II). The molar ratio of the repeated unit represented by the general formula (I) to the repeated unit represented by the general formula (II) in this polymer chain (A1) is not specifically limited but the ratio [general formula (I)/general formula (II)] is in the range of from 99/1 to 50/50, and preferably from 95/5 to 60/40. In the repeated unit represented by the above general formula (II), R3 represents a hydrogen atom, a methyl group or an aryl group which may have substituents. Specifically, phenyl, p-tolyl, 4-methoxyphenyl groups and the like can be exemplified. Also, R4 represents a hydrogen atom or a C1 through C6 alkyl group. Specifically, methyl, ethyl, isopropyl, t-butyl groups and the like can be exemplified. The letter, q represents 1 or 2 wherein R4 may be identical or different when q is 2. The substituted sites of R4 and the alkoxy group (OR5-group) are not specifically limited but the alkoxy group is preferably substituted at the para- or meta- position of alkenyl group.
R5 represents an acidolytic/leaving group. Acidolytic/leaving groups herein mean the groups which leave or decompose by acids. Specifically, methoxymethyl, 2-methoxyethoxymethyl, bis(2-chloroethoxy)methyl, tetrahydropyranyl, 4-methoxy tetrahydropyranyl, tetrahydrofuranyl, triphenylmethyl, trimethylsilyl, 2-(trimethylsilyl) ethoxymethyl, t-butylmethylsilyl, trimethylsilylmethyl, t-butyl, t-butoxycarbonyl, t-butoxycarbonylmethyl, 2-methyl-2-t-butoxycarbonylmethyl groups and the like can be exemplified. Furthermore, as R5, the groups represented by the following formula: 
wherein R14 represents the C1 through C20 alkyl group unsubstituted or substituted with alkoxy, C5 through C10 cycloalkyl group, or C6 through C20 aryl group unsubstituted or substituted with alkoxy; R15 represents a hydrogen atom or C1 through C3 alkyl group; and R16 represents C1 through C6 alkyl group or C1 through C6 alkoxy group. As such substituents, specifically, 1-methoxyethyl, 1-ethoxyethyl, 1-methoxypropyl, 1-methyl-1-methoxyethyl, 1-(isopropoxy)ethyl groups and the like can be exemplified.
Also, the above polymer chain (A1) is preferably a copolymer having the repeated unit represented by the general formula (I) and the repeated unit represented by the general formula (III). In the repeated unit represented by the formula (III), R6 represents a hydrogen atom or a methyl group; R7 represents a hydrogen atom or C1 through C6 alkyl group, specifically methyl, ethyl, isopropyl, t-butyl groups and the like can be exemplified; and r represents 1 or 2 wherein R7 may be identical or different when r is 2 wherein the substituted site is not especially limited. The molar ratio of the repeated unit represented by the general formula (I) to the repeated unit represented by the general formula (III) in this polymer chain (A1) is not especially limited but the ratio [general formula (I)/general formula (III)] is preferably in the range of from 99/1 to 50/50.
Additionally, the above polymer chain (A1) is preferably a copolymer having the repeated units represented by the general formulae (I), (II) and (III). The molar ratio of the repeated units in this polymer chain (A1) is not especially limited but the molar ratio [general formula (I)/general formula (II)+general formula (III)] is preferably in the range of from 99/1 to 50/50.
The above arm moiety (A) preferably has the polymer chain (A2) having the polymer chain (A1) and the repeated unit (A21) represented by the general formula (IV). In the repeated unit represented by the general formula (IV), R8 represents a hydrogen atom or a methyl group. R9 represents a hydrogen atom, C1 through C12 alkyl group, a hydrocarbon group having alicyclic skeletons of C3 or more which may have substituents (but, do not include a carbon of substituents in carbon number), an alkyl group having hydrocarbon groups having the alicyclic skeletons, or heterocyclic group wherein acidolytic/leaving group is preferable, and the group having t-butyl groups which can be left/decomposed by acids is more preferable. Acidolytic/leaving groups herein mean the groups which decompose and/or leave by acids.
As the above R9, specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, methoxymethyl, 2-methoxyethoxymethyl, bis(2-chloroethoxy)methyl, tetrahydropyranyl, 4-methoxytetrahydropyranyl, tetrahydrofuranyl, triphenylmethyl, trimethylsilyl, 2-(trimethylsilyl)ethoxymethyl, t-butyldimethylsilyl, trimethylsilylmethyl and the functional groups represented by the following formulae wherein u represents 0 or 1 can be exemplified. 
Further, as R9, the groups represented by the following formula wherein R17 represents C1 through C20 alkyl unsubstituted or substituted with alkoxy, C5 through C10 cycloalkyl, or C6 through C20 aryl unsubstituted or substituted with alkoxy; R18 represents a hydrogen atom or C1 through C3 alkyl; and R19 represents a hydrogen atom, C1 through C6 alkyl, or C1 through C6 alkoxy groups, can be specifically exemplified. As such substituents, specifically 1-methoxyethyl, 1-ethoxyethyl, 1-methoxypropyl, 1-methyl-1-methoxyethyl, 1-(isopropoxy) ethyl can be exemplified. 
The repeated unit in the polymer chain (A) having the repeated unit (A21) represented by the general formula (IV) may be alone or a mixture of two or more, and in the case of a mixture of two or more, it is not especially limited and may be bound by random or by a block. Further, in such a case, the molar ratio is not especially limited, but in the case of a mixture of two, any of the ratios ranging from 1/9 to 9/1 can be employed.
The above polymer chain (A2) is preferably one having the repeated unit (A21) represented by the general formula (IV) and the repeated unit (A22) represented by the general formula (V). The molar ratio of (A21) through (A22) in this polymer chain (A2) is not especially limited but the ratio [(A21)/(A22)] is of from 5/95 to 100/0, preferably in the range of from 50/50 to 99/1. In the repeated unit represented by the above general formula (V), R10 represents a hydrogen atom, a methyl group or an aryl group which may have substituents and specifically, phenyl, p-tolyl, 4-methoxyphenyl groups and the like can be exemplified. R11 represents a hydrogen atom, C1 through C6 alkyl or OR12 group wherein R12 represents a hydrogen atom, C1 through C6 alkyl or acidolytic/leaving group. As the above C1 through C6 alkyl groups, methyl, ethyl, isopropyl, t-butyl groups and the like can be specifically exemplified. As R12 in the above OR12 groups, specifically the same substituents as those exemplified as R5 can be exemplified. The letter, t represents any of the integers of 1 through 3 wherein R11 may be identical or different when t is 2 or more. The substituted sites of R13 are not especially limited but the para- or meta position of the alkenyl group is preferable in the case of the OR12 group.
The configuration of the repeated unit (A21) represented by the general formula (IV) and the repeated unit (A22) represented by the general formula (V) in the above polymer chain (A2) is not especially limited and may be any of the copolymers such as random polymerization, block polymerization and the like. Among them, the arm moiety having a polymer wherein the repeated units (A21) and (A22) are block-copolymerized by (A22) through (A21) sequentially from the central core is preferable.
The present invention can include repeated units other than the repeated units represented by the general formulae (I) through (V) as necessary. The repeated units are not especially limited so long as the repeated units are obtained from the compounds having double bond(s) capable of copolymerizing with the monomers corresponding to the general formulae (I) through (V). The repeated units not having acidic substituents such as sulfonic groups, carboxyl groups, hydroxyphenol groups and the like are preferred. As the monomers corresponding to the repeated units, the compounds containing vinyl groups, the compounds containing (meth) acroyl groups and the like can be exemplified.
As compounds containing vinyl groups, aromatic vinyl compounds containing heteroatoms such as vinyl pyridine and the like, vinyl ketone compounds such as methyl vinyl ketone, ethyl vinyl ketone and the like, vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether and the like, alicyclic vinyl compounds containing hetero atoms such as vinyl pyrrolidone, vinyl lactam and the like can be specifically exemplified.
Also, as the above compounds containing (meth) acroyl groups, (meth) acrylic amide or (meth) acrylonitrile and the like can be exemplified.
These vinyl group-containing compounds and (meth) acroyl group-containing compounds can be used alone or as a mixture of two or more. The repeated units obtained from these vinyl group-containing compounds and (meth) acroyl group-containing compounds can be contained in the alkenylphenol copolymer of the present invention by copolymerizing with the repeated units represented by the general formulae (I) through (V) by random or by a block.
The number average molecular weight of the polymer (arm polymer) chains constituting the arm moiety (A) of the star block copolymer of the present invention is not especially limited, and specifically the range of from 1,000 to 100,000 can be exemplified. When the number average molecular weight of the polymer chains constituting the arm moiety (A) is from 1,000 to 100,000, the polymer chains having a single peaked ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) at the range of from 1.00 to 1.50 is preferable.
As the central core of the star block copolymer of the present invention, polyfunctional coupling agents can be preferably exemplified, and, for example, a trifunctional or more compounds. Even in the case of bifunctional compounds, if they can form trifunctional or more compounds with polymerization, their use is not hampered. Especially, the central core wherein the polyfunctional coupling agent has a polymerization crosslinked structure is preferable.
As the above polyfunctional coupling agents, specifically, the compounds represented by the general formula (VI) such as divinyl aromatic compounds, trivinyl aromatic compounds and the like, diepoxide, diketone, dialdehyde, and the compounds represented by the following formula (X):
(CR1R2X)nR3xe2x80x83xe2x80x83(X)
wherein X represents a halogen atom, or a substituent selected from the group consisting of alkoxyl groups of carbon atoms of from 1 through 6 and acyloxyl groups of carbon atoms of from 2 to 6; R1 and R2 each represent hydrogen atoms or monovalent hydrocarbon groups of carbon atoms of from 1 to 6, and R1 and R2 may be identical or different; R3 represents a multivalent aromatic hydrocarbon group capable of having n of substituents (CR1R2X) or a multivalent aliphatic hydrocarbon group wherein n represents any of the integers 3 through 6, can be included. Also the above polyfunctional coupling agents can include at least one compound selected from the silane compounds and the like consisting of the following formulae. 
The above divinyl aromatic compounds can include but are not especially limited to, for example, 1,3-divinyl benzene, 1,4-divinyl benzene, 1,2-diisopropenyl benzene, 1,3-diidopropenyl benzene, 1,4-diisopropenyl benzene, 1,3-divinyl naphthalene, 1,8-divinyl naphthalene, 2,4-divinyl phenyl, 1,2-divinyl-3,4-dimethyl benzene, 1,3-divinyl-4,5,8-tributyl naphthalene, 2,2xe2x80x2-divinyl-4-ethyl-4xe2x80x2-propyl biphenyl. These may be used alone or in combination of two or more.
As such divinyl aromatic compounds, for example, those commercially available as mixtures with ethylvinyl benzene and the like can be used as such so long as the above divinyl aromatic compound is a major component. Also, their purity may be increased by purification as needed. Furthermore, a mixture with other double bond aromatic compounds capable of polymerizing such as styrene can be used. In this case, the mixture ratio of styrene is not specifically limited so long as it can form a crosslinked polymerization of the central core by mixing with the divinyl aromatic compound, and is in the range of from 1 to 50%, and preferably from 5 to 20% by weight.
The above trivinyl aromatic compounds can include but are not especially limited to, for example, 1,2,4-trivinyl benzene, 1,3,5-trivinyl naphthalene, 3,5,4xe2x80x2-trivinyl biphenyl, 1,5,6-trivinyl-3,7-diethyl naphthalene and the like. These may be used alone or in combination with two or more.
Also, as the above divinyl aromatic compounds and trivinyl aromatic compounds, the chemical group represented by the general formula (VI) wherein the spacer is inserted between the vinyl group and the aromatic ring can be preferably exemplified. More specifically, the compounds represented below can be exemplified. These may be used alone or in combination with two or more. 
Examples of the above diepoxide can include but are not especially limited to, for example, cyclohexane diepoxide, 1,4-pentane diepoxide, 1,5-hexane diepoxide and the like. These may be used alone or in combination with two or more.
Examples of the above diketone can include but are not especially limited to, for example, 2,4-hexane dione, 2,5-hexane dione, 2,6-heptane dione and the like. These may be used alone or in combination with two or more.
Examples of the above dialdehyde can include but are not especially limited to, for example, 1,4-butanedial, 1,5-pentanedial, 1,6-hexanedial and the like. These may be used alone or in combination with two or more.
In the above general formula (X), X represents a halogen atom, an alkoxyl group of carbon atoms of from 1 through 6, or acyloxy group of carbon atoms of from 2 through 6. The above halogen atoms can include chlorine, fluorine, bromine, iodine and the like. The above alkoxyl groups of carbon atoms of from 1 through 6 can include but are not especially limited to, for example, methoxy, ethoxy, n- or iso-propoxy and the like. The above acyloxy groups of carbon atoms of from 2 through 6 can include but are not especially limited to, for example, an acetyloxy group, a propionyloxy group, and the like.
In the above general formula (X), R1 and R2 each represent hydrogen atoms or monovalent hydrocarbon groups of carbon atoms of from 1 through 6. R1 and R2 may be identical or different. Also, multiple R1 and multiple R2 each may be identical or different. The above monovalent hydrocarbon groups of carbon atoms of from 1 through 6 can include but are not especially limited to, for example, methyl, ethyl, n- or iso-propyl groups and the like.
In the above general formula (X), R3 represents a multivalent aromatic hydrocarbon group capable of having n of substituents (CR1R2X) or a multivalent aliphatic hydrocarbon group as mentioned above. The letter n represents any of the integers of from 3 through 6. And as the compounds represented by such general formula (X), the compounds represented by the following chemical formulae can be specifically exemplified. 
In addition to the above compounds exemplified, the compounds represented by the following chemical formulae can be exemplified as polyfunctional coupling agents. 
The process for producing the star block copolymer of the present invention is not especially limited so long as it is a process by homopolymerizing by anionic polymerization using an anionic polymerization initiator as a polymerization initiator the compound represented by the general formula (VII) wherein R3, R4, R5, and q are the same as mentioned above, subsequently copolymerizing a polyfunctional coupling agent, and eliminating protection of phenol hydroxyl groups; or by homopolymerizing by anionic polymerization using an anionic polymerization initiator as a polymerization initiator a compound represented by the general formula (VII) or by copolymerizing with a compound capable of copolymerizing with the compound represented by the general formula (VII), subsequently copolymerizing a polyfunctional coupling agent and further copolymerizing a compound capable of anion polymerizing, and then eliminating protection of phenol hydroxyl groups.
In the compound represented by the above formula (VII), R3, R4, R5, and q are the same as mentioned above, and the same substituents can be exemplified. As compounds represented by the general formula (VII), specifically p-t-butoxystyrene, p-t-butoxy-xcex1-methylstyrene, p-(tetrahydropyranyloxy)styrene, p-(tetrahydropyranyloxy)-xcex1-methylstyrene, p-(1-ethoxyethoxy) styrene, p-(1-ethoxyethoxy)-xcex1-methylstyrene and the like can be exemplified. These can be used alone or in a mixture of two or more.
As the anionic polymerization initiators used in the above anionic polymerization, alkali metals or organic alkali metals can be exemplified. As alkali metals, lithium, sodium, potassium, cesium and the like can be exemplified. As organic alkali metals, alkylated, allylated and arylated compounds of the above alkali metals can be exemplified. Specifically, ethyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, sodium ethyl, lithium biphenyl, lithium naphthalene, lithium triphenyl, sodium naphthalene, xcex1-methyl styrene sodium dianion, 1,1-diphenylhexyl lithium, 1,1-diphenyl-3-methylpenthyl lithium and the like can be included.
The process for producing the star block copolymer of the present invention can include:
(1) a process by anion polymerizing the compound represented by the general formula (VII) alone or anion polymerizing the compound represented by the general formula (VII) and the compound represented by the general formula (VIII) or anion polymerizing the compound represented by the general formula (VII) and the compound having double bonds capable of copolymerizing with the compound in the presence of an anionic polymerization initiator to synthesize the arm polymer, subsequently reacting the polyfunctional coupling agent, and then eliminating the entirety or parts of the protective groups of phenol hydroxyl groups from the resultant copolymer;
(2) a process by reacting the polyfunctional coupling agent to form the polyfunctional core, subsequently anion polymerizing the compound represented by said general formula (VII) alone or the compound represented by the general formula (VII) and the compound represented by the general formula (VIII) or the compound represented by the general formula (VII) and the compound having double bonds capable of copolymerizing with the compound in the presence of an anionic polymerization initiator to synthesize the arm polymer, and then eliminating the entirety or parts of the protective groups of phenol hydroxyl groups from the resultant copolymer; and
(3) a process by anion polymerizing the compound represented by the general formula (VII) alone or the compound represented by the general formula (VII) and the compound represented by the general formula (VIII) or the compound represented by the general formula (VII) and the compound having double bonds capable of copolymerizing with the compound to synthesize an arm polymer, subsequently reacting a polyfunctional coupling agent, further reacting the monomer capable of anion polymerizing such as the compounds represented by the general formulae (IX), (VIII) and (IX) in the presence of an anionic polymerization initiator, and then eliminating the entirety or parts of the protective groups of phenol hydroxyl groups from the resultant copolymer. The above (1) and (3) are easy for controlling the reaction and preferable in terms of producing the star block copolymer of which the structure is controlled.
Additionally, the star block copolymer of the present invention can be produced by cation polymerizing the compound represented by the general formula (VII) alone or the compound represented by the general formula (VII) and the compound represented by the general formula (VIII) or the compound represented by the general formula (VII) and the compound having double bonds capable of copolymerizing with the compound, subsequently reacting the polyfunctional coupling agent, and then eliminating entire or parts of protective groups of phenol hydroxyl groups from the resultant copolymer in the presence of a cationic polymerization initiator such as triethylamine, 2-chloro-2,4,4-trimethyl-1-pentene/TiCl4 and the like.
The polymerization reaction to synthesize the arm polymer in the above process (1) or (3) can be conducted by either the method of dropping the anionic polymerization initiator into the monomer (mixed) solution or the method of dropping the monomer (mixed) solution into the solution containing the anionic polymerization initiator. The method of dropping the monomer (mixed) solution into the solution containing the anionic polymerization initiator is preferable in terms of ability to control molecular weight and molecular weight distribution. The synthetic reaction of the arm polymer is usually carried out in the organic solvents under an inert gas atmosphere such as nitrogen, argon, and the like at a temperature ranging from xe2x88x92100 to 50xc2x0 C., and preferably from xe2x88x92100 to 40xc2x0 C.
The organic solvents used in the synthetic reaction of the above arm polymer can include organic solvents usually used in anionic polymerization such as anisole, hexamethylphosphoramide, and the like in addition to aliphatic hydrocarbons such as n-hexane, n-heptane, and the like, alicyclic hydrocarbons such as cyclohexane, cyclopentane and the like, aromatic hydrocarbons such as benzene, toluene, and the like, and ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, and the like. These can be used as a single solvent or a mixed solvent of two or more. Among them, the mixed solvents of tetrahydrofuran with toluene, tetrahydrofuran with hexane, and tetrahydrofuran with methylcyclohexane can be preferably exemplified in terms of polarity and solubility.
The polymerization forms of the arm polymer can include a random copolymer in which each component is statistically distributed throughout the entirety of the copolymer chain, partial block copolymer, and complete block copolymer. Each of these can be synthesized by selecting the compound represented by the general formula (VII) described above and the additional method of vinyl aromatic compound and the like. For example, the random copolymer can be synthesized by polymerization by adding the mixture of the compound represented by the general formula (VII) and the vinyl aromatic compound into a reaction system. The partial block copolymer can be synthesized by previously polymerizing the entirety of either one and subsequently continuing polymerization by adding the other mixture or by previously polymerizing partially either one and subsequently continuing polymerization by adding the mixture of both. The complete block copolymer can be synthesized by polymerization by sequentially adding the compound represented by the general formula (VII) and the vinyl aromatic compound into the reaction system.
The reaction of the star block copolymer of which a branched polymer chain is the resultant arm polymer can be carried out by adding the aforementioned polyfunctional coupling agent to the reaction solution after completion of the synthetic reaction of the arm polymer. The polymer of which the structure is controlled and the distribution of molecular weight is narrow can be obtained by usually conducting the reaction in the organic solvent under an inert gas atmosphere such as nitrogen, argon, and the like at a temperature ranging from xe2x88x92100xc2x0 C. to 50xc2x0 C., and preferably from xe2x88x9270xc2x0 C. to 40xc2x0 C. Such generation reaction of the star block copolymer can be carried out subsequently in the solvent used to form the arm polymer, can be carried out in the solvent of which composition is changed by adding other solvents, or carried out by replacing the solvent to the other solvent. As such solvents, the same solvents can be used as those used in the synthetic reaction of the arm polymer.
In the process producing the star block copolymer of the present invention, the molar ratio [(C)/(D)] is preferably from 0.1 to 10 for the polyfunctional coupling agent (C) to an active end of the polymer chain homopolymerizing the compound represented by the general formula (VII) or an active end (D) of the polymer chain copolymerizing the compound represented by the formula (VII) and the compound capable of copolymerizing by anionic polymerization using the anionic polymerization initiator as the polymerization initiator. When polyvinyl compounds such as divinyl benzene and the like are used as the polyfunctional coupling agent, the quantity of the polyvinyl compounds to be added is preferably in the range from 0.1 to 10 equivalents, and preferably from 1 to 10 equivalents based on the amount of the active end of the arm polymer chain. The reaction of the arm polymer chain with the polyfunctional coupling agent can employ either the method in which the polyfunctional coupling agent is added to the arm polymer chain having the active end or the method in which the arm polymer chain having the active end is added to the polyfunctional coupling agent.
The number of arms of the star block copolymer is determined depending on an additional quantity of the polyvinyl compound, reaction temperature, and reaction period, and usually multiple star block copolymers with different numbers of the arm are simultaneously generated by influences of different reactivity of living polymer ends and vinyl groups and steric hindrance. As the star block copolymer of the present invention, those having three or more of the arm are preferred. The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the generated star block copolymer is preferably in the range of from 1.00 to 1.50, and the number average molecular weight of the star block copolymer is preferably from 3,000 to 300,000.
In the process (3) wherein new arm polymer chains are formed by reacting the monomers capable of anion polymerizing to the central core (polyfunctional core) having the active end formed by reacting the arm polymer chain previously adjusted with the polyfunctional coupling agent, the star block copolymer having different types of arm polymer chains can be produced. The monomer capable of directly polymerizing can be reacted to the active end present in the central core. Also the monomer can be reacted after reaction of the compounds such as diphenyl ethylene, stilbene, and the like or after the addition of alkali metals such as lithium chloride or metallic salts of alkali earth metals. The latter is sometimes advantageous in controlling the entire structure of the generated star block copolymer because the polymerization reaction is processed slowly when a highly reactive monomer such as acrylate derivatives is reacted. Also the above reaction can be carried out subsequently in the solvent used to form the central core having the active end, can be carried out in the solvent of which composition is changed by adding other solvents, or carried out by replacing the solvent to the other solvent. As such solvent, the same solvents can be exemplified as those used for synthesis of the arm polymer. Also, it is possible that random copolymerized polymer chains are made by mixing and reacting two types of monomers as the arm polymer chain newly introduced for the active end of the central core in the process (3) or as the arm polymer chain in the process (2) and that block polymer chains are made by sequentially adding two types of monomers. It is also possible that functional groups are introduced to the ends by adding carbon dioxide, epoxy and the like after completion of the reaction.
The reaction eliminating protective groups of phenol hydroxyl groups from such a resultant copolymer and generating alkenylphenol skeletons is carried out in the presence of the mixed solvent of one or more of alcohols such as methanol, ethanol and the like, ketones such as acetone, methylethyl ketone and the like, multivalent alcohol derivatives such as methyl cellosolve, ethyl cellosolve and the like, water and the like, using an acid reagent such as hydrochloric acid, sulfuric acid, hydrochloric gas, hydrobromic gas, p-toluene sulfonate, 1,1,1-trifluoro acetate, bisulfate represented by the following formula: XHSO4 wherein X represents an alkali metal such as Li, Na, K and the like as a catalyst at a temperature ranging from room temperature to 150xc2x0 C. in addition to the solvents exemplified by the polymerization reaction.
In this reaction, the protective groups of phenol hydroxyl groups are selectively eliminated entirely or partially by appropriately combining the type and concentration of the solvent, the type and additional quantity of the catalyst, and the reaction temperature and period, thereby being capable of producing the alkenylphenol star block copolymer with narrow dispersion in the present invention of which the structure is controlled.
Among the star block copolymers obtained as described above having alkenylphenol skeletons of the present invention, the arm polymer is sometimes contaminated in the final product due to incomplete reaction in the copolymer obtained from the reaction of the polyfunctional coupling agent with the arm polymer. In this case, it is possible that the arm polymer chain is eliminated as needed if physical properties of the star block copolymer are variable. The fractional reprecipitation can be suitably exemplified as an eliminating method. In such fractional reprecipitation, reprecipitation is performed preferably using a mixed solvent of high and lower polymer-soluble solvents. In the mixed solvent of high and lower polymer-soluble solvents, the method in which the star block copolymer is heat-dissolved and cooled, the method in which the star block copolymer is crystallized by dissolving in the high polymer-soluble solvent followed by adding the lower polymer-soluble solvent, and the like can be exemplified. The latter method can be also performed by appropriately heating the solvent. Lower alcohols such as methanol, ethanol, and the like as the above highly soluble solvents and water as the above lower soluble solvent are preferably exemplified in the star block copolymer. The mixed ratio of both solvents is varied depending on the star block copolymer to be purified. Its volume ratio [(highly polymer-soluble solvent)/(lower polymer-soluble solvent)] is preferably in the range of from 90/10 to 10/90 and more preferably from 80/20 to 20/80. The concentration of such solution is not especially limited, but for example, the range of from 1 to 50%, and more preferably the range of from 2 to 30% can be exemplified. When it is 1% or less, the crystallized yield is decreased due to such amounts of solvent. When it is 50% or more, efficiency to eliminate impurities is decreased. The objective star block copolymer can be taken in an almost pure form by repeating these manipulations several times.